1. Field of the Invention
This invention concerns a lens barrel configured to hold a lens for a camera or the like. The invention particularly relates to the lens barrel formed by a molding process and a metallic mold for molding the lens barrel.
2. Description of Related Art
FIG. 6 shows a prior art lens barrel. On this lens barrel, a first lens holding component 1b, which holds a lens L1, is formed on one side of an abutting joint component 1a. The abutting joint component 1a is integrally formed around the inner circumference of the cylinder-shaped barrel main body 1. The second lens holding component 1c, which holds lens L2, is formed on the other side of the same abutting joint component 1a. Generally, this type of lens barrel has been formed, for example, from the injection molding of resin, aluminum, or the like.
FIG. 7 shows the metallic mold for molding the aforementioned lens barrel. This metallic mold is made of a core 2 and a cavity 3. The outer circumference 1d of the barrel body, the second lens holding component 1c, and the abutting joint component 1a are formed by the core 2. The first lens holding component 1b is formed by the cavity 3.
However, the prior art device is characterized by insufficient optical performance because the second lens holding component 1c is formed by the core 2 and the first lens holding component 1b is formed by the cavity 3. The lens holding components 1b and 1c are formed with an eccentric condition due to the axis shift of the central axis of the core 2 and the cavity 3. This axis shift causes the lens L1, which is tightly held by the first lens holding component 1b, and the lens L2, which is tightly held by the second lens holding component 1c, to become eccentric, resulting in a loss of optical performance.